Field of the Invention
Embodiments of the invention relate to semiconductor processing in general, and in particular to a system for adjusting a mass-resolving slit during semiconductor processing applications.
Discussion of Related Art
Ion implantation is a process of depositing chemical species into a substrate by bombardment of the substrate with energized ions. In semiconductor manufacturing, ion implanters are used for doping processes that alter the type and level of conductivity of target materials. A precise doping profile in an integrated circuit (IC) substrate and its thin-film structure is important for proper IC performance. To achieve a desired doping profile, one or more ion species may be implanted in different doses and at different energy levels.
FIG. 1 is a block diagram of an embodiment of an ion implantation system 100 including an ion source 102, which is a hybrid ion source whose operation is detailed below. A power supply 101 supplies the required energy to source 102 which is configured to generate ions of a particular species. The generated ions are extracted from the source through a series of electrodes 104 (extraction electrodes) and formed into a beam 95 which is manipulated and directed to a substrate using various beam components 106, 108, 110, 112. After extraction, the beam 95 passes through a mass analyzer magnet 106. The mass analyzer is configured with a particular magnetic field such that only the ions with a desired mass-to-charge ratio are able to travel through the analyzer. Ions of the desired species pass through a mass-resolving slit assembly 107, then through a deceleration stage 108 to a corrector magnet 110. The corrector magnet 110 is energized to deflect ion beamlets in accordance with the strength and direction of the applied magnetic field to provide a ribbon beam targeted toward a work piece or substrate positioned on support (e.g. platen) 114. In some cases, a second deceleration stage 112 may be disposed between corrector magnet 110 and support 114. The ions lose energy when they collide with electrons and nuclei in the substrate and come to rest at a desired depth within the substrate based on the acceleration energy.
As noted, the mass resolving slit assembly 107 includes an aperture through which the ion beam 95 passes during the ion implant process. Through careful sizing of the aperture, the mass resolving slit assembly 107 can function to separate desired dopant ions from contamination species that would adversely affect the quality of semiconductor devices. As will be appreciated, a portion of the ion beam 95 impinges on a portion of the mass resolving slit assembly, rapidly eroding the edges of the assembly immediately adjacent to the aperture. As a result, the edge portions of the mass resolving slit assembly 107 must be replaced at an undesirably short interval.